1. Field of the Invention
The present invention relates to a magnetic recording/reproducing apparatus in which a magnetic tape is changed (e.g. from forward to reverse).
2. Description of Related Art
FIG. 1 and FIG. 2 are a schematic plan view and a rear view of the major part of a conventional magnetic recording/reproducing apparatus, respectively. A main plate 51 in a practically rectangular shape is provided, at an appropriate position (an upper left port, ion in FIG. 1), with a rotation drum 18a having a recording/reproducing head. A loading motor 7 is provided on the upper right portion of the main plate 51. On both the sides of the rotation drum 18a are provided tape guide grooves 9a and 10a through which tape guides 9 and 10 slide. A supplying reel 12 and a take-up reel 11 are disposed on the lower side and the lower right side of the rotation drum 18a, respectively. The supplying reel 12 and the take-up reel 11 are driven by reel driving gears 44 and 45, respectively. An arm-tension 15 for adjusting the tension of a magnetic tape is mounted on the side of the supplying reel 12.
In the rear view of FIG. 2, a capstan motor 25 is disposed at an upper left portion. The power from the capstan motor 25 is received by an idler gear 29a through a capstan belt 27 and a pulley belt 28, and is further transmitted to the take-up reel driving gear 45 on the side of the take-up reel 11 or the supply reel driving gear 44 on the side of the supply reel 12 through a idler gear 29b coaxially rotatable with the idler gear 29a.
Such a conventional magnetic recording/reproducing device is operated as follows: When the supply reel 12 and the take-up reel 11 are rotated in the forward direction, the power of the capstan motor 25 is received by the idler gear through the capstan belt 27 and the pulley belt 28, and is further transmitted to the reel driving gear 45 on the side of the take-up reel 11 through the idler gear 29b. When the rotation direction is changed from forward to reverse, the capstan motor 25 is rotated in the reverse direction, thereby rotating the pulley belt 28, which is connected to the capstan motor 25 by the capstan belt 27, also in the reverse direction. Then, a gear fixed so as to rotate coaxially with the pulley belt 28 engages with the idler gear 29a, thereby swinging the idler gear 29a (and 29b) toward the supply driving gear 44 on the side of the supply reel 12. Thus, the idler gear 29b that, has engaged with the take-up reel driving gear 45 is forced to engage with the supply reel driving gear 44. As a result, the supply reel 12 is driven to rewind a magnetic tape in the reverse direction.
Since neither the supply reel 12 nor the take-up reel 11 while the idlers gears 29a and 29b are moving between the supply reel driving gear 44 and the take-up reel driving gear 45, the magnetic tape is not rewound in the cassette. The capstan motor 25, however, is still rotating during the movement, and therefore, the magnetic tape continues to be fed. Therefore, the magnetic tape becomes loose, resulting in low tape tension. The tape tension is also varied by the change of the running path of the magnetic tape. When the magnetic tape is loose, noise appears on a reproduced image, thereby degrading the image.
In a conventional apparatus, the tape tension is adjusted by an arm tension 15 so as to prevent the tape from loosening when the tape tension is varied. In such a case, however, the tape still tends to be loose because the length of the running path of the magnetic tape is suddenly changed.